Most firearm training happens in the daylight, outdoors, and in a calm, orderly fashion. This is not the way bad things usually happen to us. They happen at night when you least expect them.
When you have a situation arise that you have to defend your home, several things can come into play such as low light, target identification, confined space, and above all panic because this could possibly be a life or death situation.
For home defense, a laser, and of course a good bright light helps you quickly identify your target without having to try and aim the gun with the sights.—preferably in combination with a white light—allows the homeowner to identify a threat, put the laser's dot on them "from the hip" holding a phone or your child with your weak side hand without having to assume classic double handed range target shot.
Another plus is when the threat sees a red or green dot appear on his chest, he has either a mental problem or a death wish if he or she continues to advance against you.
Some guns with lasers and lights mounted on them are hard to find holsters for concealed or open carry but there are options for grip mount styles that work well in most holsters. Also note that for home defense, keeping your weapon in a biometric gun safe is the perfect option. They open instantly with just a swipe of your fingerprint.
Put the odds in your favor and use the dot to place your shot!